Various dispensing devices have been developed where it is desirable to provide information about the number of discharges of a particular substance that have been dispensed from or remain in a container. For example, various aerosol dispensing devices have been developed that include a dose indicating device to indicate the number of metered doses that have been dispensed from the device, or to indicate the number of doses remaining therein. For example, patients have certain conditions that can be treated with medicaments dispensed in an aerosol and administered to the patient by inhalation. In one format, the aerosol with medicaments are contained in a container, and dispensed in metered, or measured, dosages with an inhalation device, or actuator boot. In such an arrangement, it can be important for the patient to be able to ascertain the number of metered doses remaining in the container, either by an indication of the number remaining therein or by knowledge of the number already dispensed therefrom, such that the patient is not caught unaware with an empty container when in need of the medicament. Thus, it may be important for the inhalation device to provide an accurate indication of either the number of doses remaining in the container, or the number of doses already dispensed therefrom.
In order to provide an accurate indication, some devices are provided with an indexing device that prevents an indicator member from inadvertently moving when the device is not being actuated, for example when the device is dropped or otherwise jarred, or if the indicator member is designed to move only upon a predetermined number of actuations greater than one. At the same time, it may be desirable to provide a relatively uniform actuation force for the dispensing device, regardless of whether the indicator member is being advanced by overriding the indexing device, or is not being advanced, for example when the indicator member is immobilized between the number of predetermined actuations.